Nor is there hard evidence of his exact age or birthplace, even though official guides list a date and pinpoint Rio de Janeiro.
"I believe I came from the highlands of Brazil ... I am very glad of the life I have had in Sweden," he said in sometimes hard-to-decipher English while sitting at his team tent amid the bustle at Western Springs.
"I know nothing of my [birth] family and naturally I would like to know more and especially if I have brothers and sisters. But I lead a busy life and haven't looked into that."
Lindback was adopted by Monica Hermansson Lindback, a brilliant Swedish skiing champion, and her husband Ola, a boss at a stainless steel plant.
Sweden is one of speedway's few strongholds. But Antonio, brought up as an only child, does not mention any rider when asked about his inspirations. He was 10 when his mother, a teacher, took him on her class' visit to speedway, and the kid was immediately entranced.
Lindback is also a fantastic skier - he can do the double back flip - but speedway won over the possibility of being a professional on the snow.
This will be his eighth season in what has become a 12-event world speedway series usually conducted exclusively on European tracks.
Western Springs, with open corners, could draw the best out of the talented Lindback in this year's opening round.
"I'm different," Lindback says, explaining that he is motivated by the racing thrill rather than mere victory hunts. Promoters wanting to spread speedway globally will hope he can enjoy both.